Antiviral agents

Influenza A pneumonitis following treatment of acute cardiac allograft rejection with murine monoclonal anti-CD3 antibody (OKT3)

A 51-year-old man developed fever, cough, and dyspnea 5 days after completing murine monoclonal anti-CD3 antibody (OKT3) treatment for acute cardiac allograft rejection. Samples of BAL fluid grew influenza A virus. Progressive pulmonary infiltrates, respiratory compromise, and hypoxia developed, and the patient ultimately required 5 days of mechanical ventilation. Treatment with amantadine hydrochloride and ribavirin was prescribed, and the patient was discharged after 19 days. Influenza A virus has not been an important pathogen in cardiac transplant recipients. However, this is the first reported case of influenza A pneumonitis complicating anti-T lymphocyte therapy for cardiac allograft rejection. In comparison with our patient, two previously reported cases of influenza A infection in cardiac transplant patients have been less severe. The virulence of our patient's, life-threatening infection appears to be secondary to impairment of T lymphocyte-mediated immunity by OKT3. The role of therapeutic and even prophylactic amantadine therapy in this clinical setting has yet to be determined.

Rimantadine: a clinical perspective

OBJECTIVE

To provide a review of rimantadine, including its antiviral activity, pharmacokinetics, efficacy, adverse effects, drug interactions, and dosage and administration. Information on influenza A virus and clinical features of influenza disease are presented. Comparative data on rimantadine and amantadine are described.

DATA SOURCES

A MEDLINE search restricted to English-language literature published from 1966 through 1994 and an extensive review of journals was conducted.

DATA EXTRACTION

The data on antiviral activity, pharmacokinetics, adverse effects, and drug interactions were obtained from various articles on rimantadine in open and controlled studies. Controlled double-blind studies were evaluated to assess the efficacy of rimantadine in prophylaxis and treatment of influenza A infection.

DATA SYNTHESIS

Over 90% of a rimantadine dose was absorbed in 3-6 hours in healthy adults. Steady-state plasma concentrations have ranged from 0.10 to 2.60 micrograms/mL at doses of 3 mg/kg/d in infants to 100 mg twice daily in the elderly. Nasal fluid concentrations of rimantadine at steady-state were 1.5 times higher than plasma concentrations, which may explain the effectiveness of rimantadine despite a low plasma concentration. Over 75% of a rimantadine dose was metabolized in the liver, and the parent compound and metabolites were almost completely eliminated by the kidneys. The elimination half-life ranged from 24.8 to 36.5 hours, which allows once-daily dosing. Dosage adjustment is recommended for patients with severe renal impairment (creatinine clearance < or = 0.17 mL/s), severe hepatic dysfunction, or elderly nursing home patients. Drug-resistant strains of influenza A virus to rimantadine occurred in several studies with children and/or adults. Clinical significance of drug-resistant strains has not been established. Rimantadine appeared to be effective in 85-90% of individuals for prevention of influenza A illness and in 50-65% for prevention of influenza A infection. Rimantadine reduced the time to a 50% reduction in symptoms by 1-3 days versus placebo. Differences in symptom reduction between rimantadine and placebo after the first 3 days of treatment was not generally clinically significant. The most common adverse effects of rimantadine administration were associated with the central nervous system (CNS) and the gastrointestinal (GI) tract. CNS-related adverse effects occurred in 3.2% of children younger than 10 years of age and 8.4% of adults. In elderly patients, the incidence of CNS-related adverse effects ranged from 4.9% at 100 mg/d to 12.5% at 200 mg/d. GI adverse effects occurred in 8.4% of children younger than 10 years of age, 3.1% of adults, and 2.9% at 100 mg/d and 17.0% at 200 mg/d in the elderly.

CONCLUSIONS

Rimantadine offers some desirable features for the treatment and prophylaxis of influenza A infection. It appears to be an attractive choice in elderly patients with a history of CNS adverse effects from amantadine and in patients with mild or moderate renal impairment. Although approved for twice-daily dosing, rimantadine has a pharmacokinetic profile that would allow once-daily dosing. It is effective for prophylaxis (not postexposure prophylaxis) and treatment of influenza A virus. It also has a low incidence of adverse effects.

Antiviral drugs

There are only a limited number of effective, non-toxic antiviral drugs for clinical use, whereas there is a great need for such drugs. Especially for the treatment of patients infected with the human immuno-deficiency virus (HIV) anti-HIV drugs are required. At the same time viral infections secondary to AIDS cannot yet be treated effectively. An increasing problem is the development of virus strains resistant to the available drugs. At this moment a great effort is made in the research for new antiviral drugs. In this article the available antiviral drugs are reviewed. Their antiviral properties, mechanism of action, clinical use, pharmacokinetic properties and side-effects are discussed. Some attention is paid to the future directions in the search for new anti-HIV drugs.

Herpetic whitlow with bacterial abscess

The herpetic whitlow should be treated nonoperatively. However, a difficult therapeutic dilemma occurs when a whitlow is seen with an established bacterial abscess. We report a case of an adult whose first herpetic whitlow was complicated by secondary periungual abscesses that progressed despite intravenous antimicrobial therapy. Surgical drainage of these periungual abscesses was successfully done in conjunction with intravenous acyclovir with no adverse effects.